A typical thickness detection device for sheet-type media generally includes a sensor and a thickness detection unit including a detecting portion and an amplifying portion. When a sheet-type medium passes through the thickness detection device, the sensor measures the movement distance of the amplifying portion of the thickness detecting unit, and then a thickness value of the medium is obtained by calculation. However, a typical thickness detection unit is complex in configuration and easy to result in measuring errors. In addition, it is difficult to determine an initial position of the sensor relative to the thickness detection unit. The accuracy of a final measuring result will be decreased due to the change of the initial position of the sensor. Some thickness detection devices in which the initial position of the sensor is adjustable have been proposed, but an adjustment mechanism therein is complicated in configuration, troublesome in the adjustment process and inconvenient in maintenance.
Thus, a need exists for an improved thickness detection device to overcome the defects mentioned above.